1. Field of the Invention
The field of the invention is devices and methods for generating and collecting energy from fusion reactions.
2. Summary of the Invention
This invention relates to adaptation of intersecting storage rings, of the same type used in high energy nuclear physics research, to produce and collect energy for use in power generation. The device is optimized for lower-energy beam particles and higher beam current, adapted with a reaction chamber at the intersection of the rings to collect released fusion energy for conversion to electricity, and equipped with means to recapture scattered accelerated particles and reintegrate them into the focused beams for recirculation through the reaction chamber.
3. Related Art
It is known that certain isotopes of hydrogen, when caused to collide with sufficient energy, will fuse to form helium. This releases substantial amounts of energy. Some examples of these reactions listed in Ref. 1 pp. 720 are as follows. EQU D+D&gt;He3+n+3.25 MeV EQU D+D&gt;T+p+4.0 MeV EQU T+D&gt;He4+n+17.6 Mev EQU He3+D&gt;He4+p+18.3 MeV EQU Li6+D&gt;2He4+ +22.4 MeV EQU Li7+p&gt;2He 4+17.3 MeV
REACTION #3 is the easiest to promote since it requires the lowest accelerated-particle energy (about 110 KEV) and has the highest cross section (about 5 barns). See FIG. 7. As indicated, where the reactants are tritium and deuterium the products include one Helium 4 nucleus, one neutron, and about 17.6 MEV of energy.
Numerous methods have been developed over the years to produce the conditions of high energy required to promote a self-sustaining thermonuclear reaction for the purpose of producing electric power.
Government projects have concentrated primarily on producing and confining plasmas (gas heated to a temperature or energy sufficient to cause the electrons to be pulled out of their orbits around the nucleus) to produce fusion. The confinement has been either of a magnetic nature, relying on the electrical conductivity of plasma, or of an inertial nature, relying on an intense laser or ion beam to rapidly heat a small fuel pellet causing it to implode. Either method results in an environment where some hydrogen nuclei will collide with each other with enough energy to fuse into helium. However, these projects have entailed enormous, continuing research and development investments in efforts to elucidate new principles of physics and to invent new devices to achieve net energy output. These projects are still attempting to reliably achieve break-even net energy balances and there is no assurance as to when, if ever, these technologies will enable reliable net energy production. Ref. 6.
Several ion colliders have been developed and are referenced below. Salisbury, Hirsch and Farnsworth rely on electrostatic confinement. Jarnagin, Post, Bennett and Maglich use magnets to bend the trajectories of the ions.
If ions are accelerated from rest to a high energy but pass through only a single intersection of opposing beams where they have an opportunity for a collision, most accelerated ions will fail to collide and the energy expended to accelerate them will be wasted, thus defeating net energy production. The energy expenditure for initial acceleration can be conserved by recirculation of the accelerated particles in intersecting storage rings for additional collision opportunities.
Hayden S. Gordon invented the intersecting storage ring device for causing atomic nuclei to collide head on and recirculating the un-reacted particles with reduced loss of un-reacted particles and resulting savings of input energy. U.S. Pat. No. 3,343,020, by Gordon, 1967. In Gordon's device nuclei are directed around one ring in one direction through an evacuated pipe with appropriate magnets to bend the paths of the nuclei and other magnets and electrodes to focus the beams of nuclei and insure that they have the correct energy. A second ring is provided to send another beam in the opposite direction. There is at least one spot where the two rings intersect. When beams of atomic nuclei collide nearly head on in the intersecting storage rings, a large percentage of the combined energy of both beams is available to cause nuclear reaction. Intersecting storage rings in one form or another have become an important tool for high energy particle research. They have also become important as intensive neutron sources according to Ref. 2 pp. 123.
At the intersection of opposing beams of accelerated particles, ions that closely approach each other without collision, the `near misses`, are mutually repelled by the electrostatic charge and are scattered over a large range of angles. When equations 1 through 6, which are based on Ref. 1 and 5, are solved for angles of closest approach between 0 and 90 degrees, Table 1 is the result. It lists the relative probability of elastic scattering as a function of the angle of scatter for deuterium by tritium at 110 KEV.
Storage rings can be adjusted to maximize collisions between bunches of deuterons and tritons, but still most of the particles will miss each other altogether, and some near-misses will be scattered. It is important to recapture as high a percentage of scattered particles as possible in order to conserve the input energy used to accelerate them. Those which are recaptured can be reintegrated into bunches with less incremental energy input than was necessary to initially accelerate them from rest. Those which are deflected so much that they cannot be recaptured must be replaced, with total loss of the input energy used to accelerate them.
Storage ring improvements have been developed to recapture some of the scattered accelerated ions and to refocus the recirculating beams which are degraded during passage through the reaction zone. Ref. 1 pp. 778 describes electrostatic and magnet lens systems arranged alternately positive and negative (in the sense of convex and concave optical elements) so that, as in the optical analog, they have a net- and strong-focusing action on charged particle beams. The most frequent appearance of such lens systems is in the form of quadrupole (four-pole) or hexapole (six-pole) magnets used as variable-focal-length, variable-astigmatism elements in beam transport both within large accelerators themselves and in extensive systems external to the accelerator.
The storage rings can be fitted with quadrupole magnets to compress the beams to a smaller diameter. Ref. 1 pp. 788. These focusing magnets also aid recapture of scattered particles.
The storage ring maintenance accelerators keep the bunches from spreading out along the axis of travel.
The hot walls of the reaction chamber will tend to emit electrons into the chamber through the process of thermionic emission. The emitted electrons would tend to obstruct the beams of deuterium and tritium. They may even be captured by nuclei in these fast moving beams. There are several ways to mitigate these thermionic emission effects. One is to install a grid inside the chamber which would be constructed out of hollow tubes. A coolant is pumped through the tubes to keep them cool, even in the very hot environment of a thermonuclear reaction chamber. The grid is negatively charged several hundred volts. This repels the electrons emitted by the walls of the chamber back toward those same walls. See FIG. 4. This is analogous to the electron tubes described in Ref. 4 pp. 261. The triode tube has a hot cathode at its center with a grid surrounding it. A plate or anode surrounds the grid. When a positive voltage is applied to the anode, electrons which are emitted by the hot cathode flow to the anode. If a voltage that is negative with respect to the cathode is then applied to the grid, the flow is reduced. If a large enough negative voltage is applied, the flow is stopped altogether. The inside walls of the reaction chamber, which will be hot, are analogous to the hot cathode. The grid in the triode is analogous to the grid in the reaction chamber, and the anode in the triode is analogous to the positive ions in the ion beams.
Devices have been developed to collect heat and kinetic energy from fusion reactions for conversion into electricity. These include the use of working fluids which absorb thermal energy and transfer it to steam turbines, impact targets which absorb kinetic energy and convert it to thermal energy, and other devices described in Ref. 9 pp. 545-549.
Reaction chambers have been devised in which thermonuclear reactions take place and the resulting energy is converted into electricity, either directly as described in Ref. 9 pp. 553-555 or by capture in the form of heat for subsequent conversion into electricity as described in Ref. 9 pp. 548. However, the combination disclosed herein of intersecting storage rings with a thermonuclear reaction chamber adapted for electric power production is new. Intersecting storage rings as described in Ref. 2 pp. 123 are used as intense neutron sources, but not for power production.
Techniques for building electrostatic lenses and mirrors, described in Ref. 7 pp. 94-98 and 103, allow the ions that are scattered by a wide angle to be recaptured and reintegrated into the beams circulated by the intersecting storage rings. The combination described herein of such electrostatic lenses and mirrors with a thermonuclear reaction chamber adapted for electric power production in intersecting storage rings is new.
An improvement in fusion energy collection efficiency can be achieved by constructing the reaction chamber with one or more membranes and a target on the outside adapted to stop helium nuclei produced in the chamber. Ref. 9 pp. 553-555. See FIG. 6. The target is supported by insulators and a large positive static charge is allowed to build up on the target. When this charge builds to about 1.6 million volts it is bled off through power converter circuits of the type used on high voltage DC power transmission lines. As the Helium 4 nuclei, which each have two positively charged protons, move toward the positively charged target, they will slow down as they do work and give up energy. They will still hit the target with substantial kinetic energy, some of which can be converted directly into electricity. Ref. 9 pp. 553-555. Since these ions (HE4+) have passed through the metallic inner chamber wall of the reaction chamber before entering the space between said wall and the target said metallic wall will tend to shield the colliding beams of ions inside it from electrostatic distortion effects. The kinetic energy of the HE4+ ions is a significant fraction of the total energy released in the reaction chamber. If other energy released in the fusion reaction also is collected and is used in a thermal cycle, such as a steam turbine, then a significant fraction, perhaps up to 50%, of the fusion energy produced in the reaction chamber could be converted into electricity. If fuels which produce no neutrons were to be used (such as Helium 3 and deuterium), then the conversion rate potentially is even higher. However, the higher accelerated-particle energy necessary to cause these heavier nuclei to fuse is a significant disadvantage to use of these fuels.
Currently disclosed reactor designs do not provide for recapture of accelerated nuclei that are scattered with deflections greater than 90 degrees. The power amplification factor of the reactor can be improved substantially by recapturing some of the accelerated nuclei that are deflected by more than 90 degrees (`wrong-way ions`) whose large deflection angles cause them to exit the reaction chamber through the `wrong` exit pipe. Wrong-way ions mixed in with the proper ions that belong in a particular pipe when they pass through the accelerating electrodes, but the mass number of the wrong-way ions would differ from that of the ions properly in that pipe. At the first bending magnet the wrong-way ions would be lost because their mass-to-energy ratio would differ from that of the proper ions for which the bending magnets are adjusted so that such wrong-way ions would not be deflected by the same angle as the proper ions' beam pipe is bent to accommodate. Ref. 4 pp. 577-579. Wrong-way tritons, for example, would collide with the outer radius of the bent portion of the deuterium pipe. Similarly, wrong-way deuterons would collide with the inner radius of the tritium pipe. If, however, bypass pipes are provided to capture these wrong-way ions and send them back into the proper beam from whence they came in accord with this invention, the power amplification factor will be increased substantially.